Fluidic fuel injection with bistable valve

ABSTRACT

A TIMED LOW-PRESSURE FUEL INJECTION SYSTEM OF THE TYPE INJECTING DISCRETE INTERMITTENT SQUIRTS OF FUEL AT SEVERAL LOWPRESSURE ENGINE LOCATIONS IN TIMED RELATION TO THE ROTATIONAL CYCLE OF AN INTERNAL COMBUSTION ENGINE. THE INVENTION IS PARTICULARLY CHARACTERIZED BY THE USE OF POSITIVELY DRIVEN BISTABLE FLUIDIC ELEMENTS TO PERFORM THE FUEL INJECTION FUNCTION AND TIMED PULSE GENERATNG MEANS TO DRIVE THE BISTABLE ELEMENTS TO THEIR INJECTING AND NONINJECTING OR OFF STATES.

United States Patent [72] Inventor Janus: S. Sulich 2,918,911 12/1959Guiot 123/32(E-1) Southfield, Mich. 3,366,370 1/1968 Rupert 123/119X121] AppLNo. 847,597 3,389,894 6/1968 Binder..... 261/36 [22] FiledAug.5, 1969 3,395,682 8/1968 Jackson... 123/139 [45] Patented June 28,1971 3,487,820 l/l970 Clark....... 123/119 [73] Assignee The BendixCorporation 3,501,099 3/1970 Benson 123/32(E) Primary Examiner- LaurenceM. Goodridge [54] FLUDIC FUEL INJECTION WITH STABLE Att0meys William S.Thompson, Plante, Arens, Hartz, Hix

' VALVE and Smith 4 Claims, 5 Drawing Figs.

[52] U.S.Cl. [23/119,

23/140FG, 123/14QMQ261/36A ABSTRACT: A timed 1ow-pressure fuel injectionsystem of [51] Int. Cl F02d 7/00 the type injecting discreteintermittent Squirts f f l at 0 Search everal low-pfes5u e enginelocations in timed relation to the 0 l 261/36 rotational cycle of aninternal combustion engine. The invention is particularly characterizedby the use of positively [56] References (med driven bistable fluidicelements to perform the fuel injection UNITED STATES PATENTS functionand timed pulse generating means to drive the bista- 2,077,259 4/1937Planiol 123/32(E) ble elements to their injecting and noninjecting oroff states.

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W381 g gpunu FLUIDIC FUEL INJECTION WITI-I BIS'IABLE VALVE BRIEF SUMMARYOF INVENTION Fuel injection devices which inject fuel at a plurality oflocations and preferably at or in each engine cylinder produce nearlyoptimum fuel management with both good performance and the production ofvery low exhaust emissions. However, such systems tend to be complex,requiring means for initiating an injection at each cylinder at theproper time, computer and sensor means for determining the desiredamount of fuel, a highly accurate injector valve at each cylinderinjector location and associated fuel pressurizing and pumping means.The cost and complexity of such systems has retarded their acceptanceeven in the face, of clear performance advantages. Progress is beingmade with the aid of solid state and integrated circuit electronicelements in reducing the size and cost of pulse initiating and computercontrols, but such devices have required in the past a number ofexpensive electronically actuated injection valves having highlyoptimized transient response times as the final control and injectiondetermining element. Accordingly, it is an object of the presentinvention to provide an injection system utilizing lowcost fluidicelements as the fuel injector determining element.

BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a functional block diagram of afuel injection system in which the features of the present invention maybe most efficiently utilized.

FIG. 2 is a schematic diagram of a pulse determining and distributionnetwork for producing time pulses at each injector location of aduration responsive to an input signal.

FIG. 3 represents a fluidic and mechanical sensing and computing circuitfor generating an analogue control signal to be applied to thedistribution device of FIG. 2.

FIGS. 4 and 5 show schematically two modifications of a portion of thepulse determining and distribution network.

DETAILED DESCRIPTION FIG. 1 represents in functional block form a fuelmanagement system in which the novel features of my invention can beutilized. The system shown is particularly directed to an automotiveengine control, but, as will be readily understood, could be applied tomany other systems with only minor modifications within the scope ofthis invention.

The four blocks 10, I2, 14 and 16 forming the leftmost column in FIG. 1,represent the several input parameters derived from the engine andstarting circuit and provide the intelligence from which the controlsystem operates. As

labeled, the system utilizes manifold pressure 10, engine temperature12, starting switch 14 (on/off) and engine speed 16 informationrespectively.

Sensor 18 represents a device which monitors manifold pressure (vacuum)and produces a usable fluid signal in the output passage 20 proportionalto the manifold pressure over the full range of variations throughoutall conditions of engine operation.

For an automotive engine, it is desired at or near wide open throttleconditions to enrich the fuel/air ratio for maximum power. At wide openthrottle conditions, manifold vacuum decreases to its lowest value andbegins to approach atmospheric pressure. Thus, manifold vacuum orpressure may be' utilized as a suitable parameter to indicate awide-open throttle condition. In the block schematic, sensor 22 istermed the wide open throttle switch and senses manifold pressure toproduce an output signal in passage 24 only during that portion inengine operation where power enrichment is desired.

Two engine temperature sensors are provided, one termed warmup sensor 26and the other labeled cold-start enrichment sensor 28. Warmup sensor 26provides a proportional signal in output passage 30 to control thedegree of fuel enrichment required due to the cold engine condition. Thesensor 28 senses temperature and is connected to the starting switch toprovide an enrichment only during engine cranking at the beginning of astarting phase. During cranking, an output signal is produced in passage32 when starting enrichment is required.

System sensors are completed with engine speed sensor 34 which producesin passage 36a signal proportional to engine speed. In the general case,the speed signal will not be usable in the form derived by sensor 34 andwill require correction to a unique nonlinear function to satisfy therequirements of a particular engine and control system. Speed correctionis, therefore, obtained by function generator 38-which produces in theoutput passage 40a corrected and usable speed signal.

All these sensor signals are supplied to a signal summer 42 whichcombines the signal to produce one output analogue control signal inoutput passage 44 representative of the desired amount of fuel at eachinstant of time it is desired to deliver to the engine.

The fuel demand signal transmitted by passage 44 is received by adistributor device 46 which distributes discrete intermittent fuelpulses to each engine mounted injector symbolically indicated by thehorizontal lines designated by numeral 48. The distributor 46 alsoperforms the functions of determining the timing of the pulse and isduration responsive to the command signal supplied by passage 44.

Referring now to FIG. 2, the distributor and pulse determining networkis shown in functional detail and is designated by numeral 46. It isoperative with a bank of six fluidic injectors designated by numeral 48and receives a demand signal designated by numeral 44. Six injectors areshown by way of example as any number may be used in the practice of myinvention. By Fluidic" is meant that class of devices growing out of thetechnology wherein sensing, control, information processing, and/oractuation functions are performed solely through the use offluid dynamicphenomena," as quoted from Fluidic Systems Design Guide First Edition,1966, Appendix C Page 147.

. Each of the fluidic injector valves 480 through 48f respectively, arecomprised of a bistable fluidic element, for example, of the typesdescribed in U.S. Pats. Nos. 3,396,619 or 3,425,430.

Fuel at a regulated pressure is supplied to the power jet passagesdesignated by numerals 50a through 50f respectively at a regulatedconstant pressure. Confining the discussion to bistable fluidic element48a, pressurized fluid is ejected by power jet nozzle 52a into a regioncommunicating with an apex of two outlet passages 54a and 56a so as todeliver fuel into either one or the other of the outlet deliverypassages. Passage 540 may be considered a return passage to the fuelstorage or tank member. Outlet passage 56a would preferably eject fuelinto the intake manifold or engine block immediately upstream of thecylinder or intake valve to provide a point of injection close to thecylinder, but nevertheless, in a lowpressure region. The dashedhorizontal lines on each output passage 54a and 56a are symbolicrepresentations of wall attachment phenomena more fully disclosed in thebeforementioned U.S. Pat. No. 3,396,619 and often referred to as theCoanda effect" after Henri Coanda who described the principle in U.S.Pat. No. 2,052,869. It should be borne in mind that The wall attachmentphenomena is but one means to achieve a bistable fluidic element whichalso may be accomplished, for example, by the use of feedback passagesas described in U.S. Pat. No. 3,425,430. The effect of the wallattachment phenomena is that the control fluid stream issuing from powernozzle 52a will seek either passage 54a or 56a, but not bothconcurrently. That is, it will tend to switch between one or the otherin a bistable manner. The fluid issuing out of passage 56a for example,would attach itself to a sidewall and continue to issue from this outletpassage until positively switched by a control signal.

Fuel is also taken from supply port 50a and transmitted through orifices58a and 60a to control passages 62a and 64a respectively. The controlpassages 62a and 64a connect with control jets 66a and 68a respectively,which eject fluid within the fluidic element transversely to the mainpower jot 52a producing a control force operative to switch the mainfluid beam between the passages 54a and 56a. Control passage 62a isconnected to a ring manifold 70 and terminates in an opening 720 whichis arranged circumferentially in a sequential order with similaropenings 72b through 72f. Openings 72a, 72b, 72c, 72d and 722 asillustrated in the drawing are all vented to a low-pressure areaproviding a low-pressure control fluid in conduits 62a and 62frespectively. Opening 72f is, however, covered by a projection 74 formedon rotating cam 76. Cam 76 may, for reference purposes, be termed astart-ofinjection cam. As passage 72f is closed, pressure in passage 62fsharply increases forming a control pulse at control jet 66f whichdeflects the main fluid stream out of outlet passage 56f. Control jetpassages 64a through 64f are connected to manifold ring 78 in acircumferentially arranged manner terminating with orifices 80a through80f respectively. End-of-injection detennining cam 82, with projection84 formed thereon, is operative to sequentially close openings 80athrough 80fin the same manner as projection '74 of cam 76. In fact, cams76 and 82 may be formed integrally or be extensions of one another. Asprojection 84 closes opening 80f, a control pulse appears in passage 64fand also at control jet 68f switching the main power jet to returnpassage 54f thus terminating the injection at injector 48f. The phaserelationship between cams 76 and 82 respectively determines the timeduration of injection at an injector valve. Manifold ring 78 isrotatable to a small degree to alter the phase relationship and thus theduration of injection to meet the various fuel demands of the system.Bellows 86 and 88 are arranged in opposing relationship and connected torod 90 to position manifold 78 a small angular degree in response to adifferential pressure signal applied via passage 92 and 94 to thebellows. The differential pressure signal to passages 92 and 94 issupplied by the signal summer 42 illustrated in the block diagram ofFIG. 1. Hydraulic, mechanical, electrical, pneumatic or fluidic signalgenerating means maybe used to position the manifoldring 78 in responseto a demand flue signal. It is noted at this point that to combinecertain electronic and fluidic techniques may provide an optimum fuelinjection system. Engine intelligence may be combined and computed in avery compact electronic system or computer and then applied to a fluidicfuel distribution system such as illustrated in FIG. 2 to avoid thecomplexity and cost of solenoid operated injection valves.

In the case shown, fluidic injection at each engine cylinder has adiscrete time of injection which occurs at the optimum point in thefiring cycle at each engine cylinder. Thus, the

system is capable of accomplishing fully timed fuel injection for allcylinders. To obtain control simplicity or provide greater availablepulse time, simpler systems have been suggested in the electronic art ofinjecting simultaneously to a group or all of the cylinders withoutsubstantially degrading engine performance. Simultaneous or groupedinjection may, of course, be readily accomplished by the-present systemsimply by actuating the start-of-injection control signals to more thanone of the fluidic injectors simultaneously. FIGS. 4 and show passagearrangements as would be used for twogroup and simultaneous fuelinjection systems respectively. Illustrated portions of FIGS. 4 and 5correspond to that illustrated in FIG. 2 andbear the same identifyingnumerals.

Referring now to FIG. 3, a system for sensing, computing and deriving ananalogue fuel demand signal is shown. The various elements have the samenumerals assigned to them in the block diagram of FIG. I. A rotativesignal indicative of engine speed 16 is supplied to shaft 102 whichrotates disc 104 of vortex type fluid in sensor 34. Rotation'of disc 104causes an addition of tangential momentum to the source flow, suppliedfrom source 106, such that a vortex action occurs resulting in avariation of the signal in transmitting passage 36, proportional to thespeed of disc 104. Pressurized control fluid, supplied from source 106,is used to preset the sensitivity of the vortex speed sensor 34. Theprinciples are more fully described in U.S. Pat. No. 3,347,103 issuedOct. 17, 1967 which describes a similar speed sensor. Excess fluid whichis not utilized in the signal transmitting passage 36 is collected inthe receiving chamber and returned to a supply tank. The fluid speedsignal is transmitted to function generator 38, which contains a movablepiston 112 and return bias spring 114, which urges the piston inopposition to the fluid speed signal pressure applied to chamber 116.Movable piston 112 contains a center land 118 having a profiled orcontoured opening 120 which is in the path of the flow of supply fluidfrom inlet passage 122 to outlet passage 40 to provide a unique functionwhich may be controlled by proper shaping of the orifice 120. It isanticipated that a speed correction may be implemented by properprofiling of the orifice 120. Most engines usually require some form ofcorrection with speed because of changes of engine volumetric efficiencyand varying air flow dynamic corrections. This correction is empiricalfor a specific engine and is usually nonlinear.

Manifold vacuum is supplied to receiving passage 10 and transmitted tosensor 18 which consists of an evacuated bellows 124i operative toposition a movable orifice 126 on tube 128 which controls the supply offluid from a supply source 130 to outlet passage 20. The fluid pressurein passage 20 will vary in value with all variations of manifold vacuum.Manifold vacuum is also transmitted to wide open throttle sensor 22which is a monostable fluidic element having its stable flow out outputleg 132. Regulated power fluid is supplied from power jet 134, and inthe absence of control signals, would attach itself to the wall ofoutput passage 132. Control jets 136 and 138 are provided which arevented to the atmosphere and connected to the manifold vacuum sourcerespectively. For most part throttle and idle throttle conditions,manifold vacuum at control jet 1.38 is sufficiently high to overcome thewall attachment phenomena in passage 132 and switch the control jet outvent passage 140. As wide open throttle condition is approached,manifold vacuum decreases to the point where it is incapable ofmaintaining the power stream deflected out of its unstable port 140 andthe power stream begins to deflect and be received in outlet passage 132where it is operative over a selected range to produce a signal inoutlet passage 24.

An enrichment signal is provided for correcting fuel/air ratio duringcold engine starting. Regulated fluid supply pressure is supplied topassage 142 and is conveyed by transmitting passage 144 to the normallyclosed solenoid operated valve 146. Electrical leads M8 and to thesolenoid 152 are in the circuit containing the starter switch and wouldapply energizing potential during the period that the automotive starterswitch is depressed. Energization of the solenoid 152 opens valve 146permitting a control signal to be transmitted to outlet passage 32 whencold start enrichment is required.

Bimetallic temperature sensing rod 154 is in a location to sense enginetemperature. Rod 162 is attached to bimetallic rod 154 and controls thevariable orifice 184 to provide cold start enrichment proportional toengine temperature. Should the engine be hot prior to cranking,bimetallic rod 154 will cause orifice 184 to be closed so'that no fuelenrichment is provided during cranking when the engine is hot. Forengine unloading during start, that is clearing out a flooded engine,rod 156 is connected to the air throttle valve so that at wide openthrottle, switch 158 is open and solenoid valve 152 for cold startenrichment remains closed and there is no signal in line 32.

It is also desired to have temperature correction of the fuel ratioduring engine running. A proportional control valve 160 having avariable orifice, generally designated by the arrow, is controlled bythe rod 162 also attached to the temperature sensor 154. The pressuresupplied to warm up sensor 26 is thus varied proportionately withtemperature. A speed signal is applied to control jet 164 of the fluidicelement 26 to provide a speed corrected temperature signal to the outputpassage 30. The speed signal proportionately reduces the degree ofenrichment increasing engine speed. The various processed signalscontained in each of the output passages 20,

24, 30, 32, and 40 are each divided into a pair of branch passagesbearing the 'same numeral but with subscripts a and b respectively.These signals are supplied as two control inputs to the signal summer42. Signal summer 42 consists of two fluidic vortex elements designatedby numerals 42a and 42b respectively which receive a power fluid streamfrom a common source 170 through branch passages 172 and 174respectively and power jets 176 and 178 which inject transversely into acircular vortex changer. Fluid is also supplied to control jets 180 and182 to provide a clockwise vortex fluid flow within the element 420 anda counterclockwise vortex flow within the element 42b. Vortex element42a receives control signals from passages 40a, a, 24a, and 300 whichare arranged to inject control signals tangentially into the vortexchamber in a direction aiding the flow established by control jet 180.in vortex fluidic element 42b, the control jet signals from the controlpassages 40b, 20b, 24b, b, and 32b, inject signals into the vortexchamber in a direction opposing the direction the vortex flowestablished by control jet 182. The two vortex control elements 42a and42b are thus arranged in pull-push relationship amplifying signalchanges in the output passages 44a and 44b respectively which are thentransmitted to bellows 86 and 88 previously described; The arrangementof two vortex amplifiers minimizes the effects of the pressurevariations at the supply 170 as these effects are balanced out andneutralized. In operation, the sensor computing and summing circuitillustrated in FIG. 3 gives a fuel demand signal for all engineconditions including the starting, idle warmup, part throttle and wideopen throttle conditions. Referring back to the distributor device ofH6. 2, the fuel demand signal is used to rotate the manifold 78 alteringthe relationship between the start of injection signal and the end ofinjection signal. As will be apparent, an intermittent flue injectionsystem without solenoid injection valves has been obtained.

lclaim:

l. A fuel injection system for an internal combustion engine having anair intake passage and at least one cylinder, said fuel injection systemcomprising:

a bistable fluidic injector valve arranged to inject fuel into alow-pressure region upstream of an associated engine cylinder;

a fuel supply source for supplying fuel to the bistable fluidic injectorwhich is diverted to one passage during an inject state and to a returnpassage during the off state of the fluidic injector;

means driven in relation to engine speed operative to generate a firststart of injection control signal and a second end of injection controlsignal, said means being connected to the fluidic injector valve so thatsaid control signals are operative to switch said fluidic injector fromthe off to the inject state and from the inject to the off state inresponse to the start of injection and end of injection control signalsrespectively;

control means determining engine fuel requirements operatively connectedto said last named means to control the time duration between start andend of injection signals.

2. A fuel injection system for multicylinder internal combustion enginescomprising:

a plurality of bistable fluidic injector valves, one for each enginecylinder arranged to inject into a low-pressure region upstream of itsassociated cylinder;

a fuel supply source for supplying fuel to each injector;

a pair of control jets for each injector to supply start of injectionand an end of injection control signals respectivey;

first means driven in relationship to engine speed connected to one ofsaid pair of control jets to provide a control signal operative toswitch said bistable fluid injectors to the inject state in timedrelationship with an engine operating cycle;

second means driven in relationship to engine speed connected to theother of said pair of control jets to provide a control signal operativeto subsequently switch said bistable fluid injectors to the off state;means responsive to engine fuel demand operatively connected to saidsecond means to control the time duration said bistable fluidic elementsare in the inject state.

3. A fuel injection system as claimed in claim 2 wherein:

said first and second means comprise a pair of cams adapted to berotatively driven in proportion to engine crank shaft speed.

4. A fuel injection system as claimed in claim 3 wherein:

each of said first and second means includes an associated annularmanifold with annually arranged control ports for each fluidic injectorarranged sequentially in injector firing order sequence, said cams andcontrol ports cooperative to generate start of injection and end ofinjection control pulse respectively.

